It sounds like Unifund bought the debt and now they are suing you. This is not illegal.
Are you claiming this is not your debt? What is your defense to the claim? What do you want to countersue for?
In your answer, you must admit or deny all numbered paragraphs. You should also include affirmative defenses or new matter to include your defenses (i.e., Statute of Limitations, etc.).
Good luck.

